1. Field of the Invention
The present invention relates to a three-dimensional visual sensor which acquires three-dimensional information on an object and applies to, for example, a three-dimensional visual sensor used for three-dimensional measurement of assembly parts, etc.
2. Description of the Related Art
Conventionally, a three-dimensional visual sensor provided with a projector and a light receiver is widely known. This conventional type three-dimensional visual sensor carries out three-dimensional measurement of an object using only three-dimensional information obtained from reflected light of pattern light (slit light, spotlight, etc.) projected onto the object. However, such an information acquisition system has problems as follows:    (1) Pattern light must always be irradiated precisely onto a part to be measured on the object. Furthermore, even when the object has a flat surface, the inclination of the surface can be calculated, whereas the position is unknown.    (2) It is only information on the projected part that can be acquired and information acquired as features is quite limited such as end points of a line, and therefore this system is likely to lack quality in aspects of noise robustness and accuracy.
As described in Japanese Patent Application Laid-Open No. 60-183509, there is an attempt to perform surface measurement by determining contours of an object in a two-dimensional image and an intersection of slit light. However, even this technique cannot solve the above-described problem (1) and requires post-processing to improve the accuracy, which takes an extra processing time. Furthermore, with respect to the above-described problem (2), when noise occurs in the intersection, the problem cannot be said to be solved by the technique of the above-described patent document.